Current HIV vaccine candidates elicit reasonably potent cellular immune responses, but only low levels of neutralizing antibodies. Such CTL based vaccines (e.g., those based on DNA immunization) do not prevent infection, but can have a beneficial effect on disease course. In contrast, passively infused antibodies can provide complete protection, but must be administered in doses that result in serum antibody levels much higher than can be generated by current immunization strategies. In order to assess if CTL could combine with antibody to produce sterile immunity, we studied the effect of a suboptimal dose of neutralizing antibodies in animals with active immunity induced by IL2 adjuvanted DNA immunization. Using a SHIV-challenge model, this study has shown that passively infused antibody can protect against an intravenous challenge.